O-ring for gas turbine engine

Exemplary embodiments of the present disclosure pertain to the art of gas turbine engines.

Traditional fluorocarbon O-rings, for use with engine oil, are limited to temperatures below ˜350 F. Some specially designed materials can be used at higher temperatures, up to 500 F, however the mechanical properties are those materials differ significantly from the existing standard fluorocarbon O-rings. Most notably, the thermal expansion of the new material is much greater.

O-rings using the new material must typically be used with a modified gland size to accommodate an increase in thermal expansion of the O-ring material. ie: the gland size must be larger. If a smaller size O-ring of the new material was defined to fit into an existing gland size, it would not meet the minimum pinch requirements of the O-ring.

In one exemplary embodiment, a seal arrangement of a gas turbine engine, includes a first component and a second component abutting the first component. An O-ring is positioned in a gland volume defined between the first component and the second component. The O-ring has a hollow circular cross-sectional shape including a ring inner diameter and a ring outer diameter, with a hollow portion defined by the ring inner diameter. The ring inner diameter of the cross-sectional shape is defined as a function of a gland outer diameter, a gland inner diameter and a gland width.

Additionally or alternatively, in this or other embodiments the O-ring is configured to operate at temperatures greater than 350 degrees Fahrenheit.

Additionally or alternatively, in this or other embodiments the first component includes a seal groove at least partially defining the gland volume.

Additionally or alternatively, in this or other embodiments the ring inner diameter is in a range of 0.2-0.4 times the ring outer diameter.

Additionally or alternatively, in this or other embodiments the ring inner diameter is determined by Formula 1.

Additionally or alternatively, in this or other embodiments the first component and the second component are disposed at a bearing assembly of the gas turbine engine.

In another exemplary embodiment, a gas turbine engine includes a combustor, and at least one spool. The at least one spool includes at least one rotating component driven by products of the combustor, and a bearing assembly supportive of the at least one rotating component. The bearing assembly includes a seal arrangement including a first component, a second component abutting the first component, and an O-ring positioned in a gland volume defined between the first component and the second component. The O-ring has a hollow circular cross-sectional shape including a ring inner diameter and a ring outer diameter, with a hollow portion defined by the ring inner diameter. The ring inner diameter of the cross-sectional shape is defined as a function of a gland outer diameter, a gland inner diameter and a gland width.

Additionally or alternatively, in this or other embodiments the O-ring is configured to operate at temperatures greater than 350 degrees Fahrenheit.

Additionally or alternatively, in this or other embodiments the first component includes a seal groove at least partially defining the gland volume.

Additionally or alternatively, in this or other embodiments the ring inner diameter is in a range of 0.2-0.4 times the ring outer diameter.

Additionally or alternatively, in this or other embodiments the ring inner diameter is determined by Formula 1.

In yet another exemplary embodiment, a method of assembling a seal arrangement of a gas turbine engine includes at least partially defining a gland volume at a first component the gas turbine engine, and installing a high-temperature O-ring into the gland volume. The high-temperature O-ring has a hollow circular cross-sectional shape including a ring inner diameter and a ring outer diameter, with a hollow portion defined by the ring inner diameter. The ring inner diameter of the cross-sectional shape is defined as a function of a gland outer diameter, a gland inner diameter and a gland width. A second component of the gas turbine engine is installed over the high-temperature O-ring and the first component, to at least partially compress the high-temperature O-ring.

Additionally or alternatively, in this or other embodiments a fluorocarbon O-ring is removed from the first component before installing the high-temperature O-ring to the first component.

Additionally or alternatively, in this or other embodiments the high-temperature O-ring is configured to operate at temperatures greater than 350 degrees Fahrenheit.

Additionally or alternatively, in this or other embodiments a seal groove is formed in the first component to at least partially defining the gland volume.

Additionally or alternatively, in this or other embodiments the ring inner diameter is defined in a range of 0.2-0.4 times the ring outer diameter.

Additionally or alternatively, in this or other embodiments the ring inner diameter is defined by Formula 1.

Additionally or alternatively, in this or other embodiments the first component and the second component are located at a bearing assembly of the gas turbine engine.

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

schematically illustrates a gas turbine engine. The gas turbine engineis disclosed herein as a two-spool turbofan that generally incorporates a fan section, a compressor section, a combustor sectionand a turbine section. Alternative engines might include other systems or features. The fan sectiondrives air along a bypass flow path B in a bypass duct, while the compressor sectiondrives air along a core flow path C for compression and communication into the combustor sectionthen expansion through the turbine section. Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with two-spool turbofans as the teachings may be applied to other types of turbine engines including three-spool architectures.

The exemplary enginegenerally includes a low speed spooland a high speed spoolmounted for rotation about an engine central longitudinal axis A relative to an engine static structure.

The low speed spoolgenerally includes an inner shaftthat interconnects a fan, and a low pressure turbine. The high speed spoolincludes an outer shaftthat interconnects an impellerand high pressure turbine. A combustoris arranged in exemplary gas turbinebetween the impellerand the high pressure turbine. An engine static structureis arranged generally between the high pressure turbineand the low pressure turbine. The inner shaftand the outer shaftare concentric and rotate about the engine central longitudinal axis A which is collinear with their longitudinal axes.

The core airflow is compressed by the impeller, mixed and burned with fuel in the combustor, then expanded over the high pressure turbineand low pressure turbine. The turbines,rotationally drive the respective low speed spooland high speed spoolin response to the expansion. It will be appreciated that each of the positions of the fan section, compressor section, combustor section, and turbine section, may be varied. While the structure described herein is a two-spool gas turbine engine, one skilled in the art will readily appreciate that the present disclosure may be similarly applied to a single spool or three or more spool gas turbine engine.

The low speed spooland the high speed spoolare supported by one or more bearing assemblies. Referring now to, to retain lubricant at the bearing assemblyand reduce undesired leakage of lubricant out of the bearing assembly, seals such as O-ringsare utilized. The O-ringis configured to seal between a first componentand a second component. In some embodiments, the O-ringis at least partially positioned in a seal grooveof the first componentand extends circumferentially about the engine central longitudinal axis A. When the second componentis installed to the first component, the seal grooveand the second componentdefine a glandin which the O-ringis positioned. With the second componentinstalled to the first componentthe O-ringis at least partially compressed in the gland. The glandhas a gland inner diameter defined at a seal groove baseof the first component, and has a gland outer diameter defined by a radial inner surfaceof the second component. Additionally, the glandhas a gland width defined by an axial groove widthof the seal groove.

It is desired to replace existing fluorocarbon O-rings on engines in service with newer higher temperature capability O-rings, with no modifications to the first componentand the second component. In some embodiments, due to differences in materials the thermal expansion of the O-ringis greater than that of the fluorocarbon O-ring that the O-ringis replacing. In some embodiments, the difference in thermal expansion is 2×, meaning that the O-ringexpands twice as much as the fluorocarbon O-ring at the operating temperature of the O-ring. Thus, the O-ringwill need to be sized and configured to account for the difference in thermal expansion, while still ensuring that pinch requirements of the O-ringare also met.

An embodiment of an exemplary O-ringis illustrated in. The O-ringhas a circular, hollow cross-sectional shape. The cross-sectional shape includes a ring outer diameterand a ring inner diameter, with the seal material disposed between the ring inner diameterand the ring outer diameter. A hollow portionof the cross-sectional shape is defined radially inboard of the ring inner diameterrelative to a cross-sectional centerof the cross-sectional shape.

When replacing a fluorocarbon O-ring with the O-ringformed from a high temperature material in the structure, the ring outer diameterof the O-ringis the same as that of the fluorocarbon O-ring that it replaces. This is done in order for the O-ringto fit within the existing glandspace and the ring inner diameteris thus sized to provide a desired hollow portionsize so the O-ringmeets the pinch requirements and/or other performance characteristics of the O-ring. In some embodiments, the ring inner diameteris sized via the following Formula 1:

The ring inner diameter, which defines the hollow portion, is a function of the gland outer diameter, the gland inner diameter, and the gland width, as previously defined herein. In some embodiments, the resultant ring inner diameteris in a range of 0.2-0.4 times the ring outer diameter. The formula is based on a nominal 75% fill ratio, where fill ratio is defined as a ratio of O-ring cross-sectional area to gland cross-sectional area. Additionally, in some embodiments the high temperature material is defined as one having a coefficient of thermal expansion equal to or greater than 0.00022 in/in/degF.

By way of example, in one embodiment it is desired to replace an O-ring having an outer diameter of 0.103″ with an O-ringhaving a hollow cross-section. At this location, the gland outer diameter is 1.44125″, the gland inner diameter is 1.276″ and the gland width is 0.140″. Using Formula 1, the desired ring inner diameterfor the O-ringis 0.027″. The resulting O-ringhas a hollow, circular cross-sectional shape with a ring outer diameterof″ and a ring inner diameterof 0.027″. The resultant O-ringformed from the high-temperature capable material seals the glandwhile meeting the pinch requirement and other performance requirements of the O-ring.

The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of +8% or 5%, or 2% of a given value.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, element components, and/or groups thereof.

While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.